A: Torrent supplies data for a range of air methods including NIOSH, OSHA, ASTM, and EPA Air Compendium Methods (TO, CO, IO). Our Project Management department is constantly bringing new methods on line, so if your request is not listed, give us a call. We may be able to offer the method you need or suggest an alternative. More

Q: What is the difference between TO14A and TO15?

A: TO14A is a GC method with specific sampling protocols. While it is very effective for some compounds, others of current concern, including Naphthalene and TBA, are not recovered well or at the necessary detection limits. TO-15 identifies compounds by GC/MS, allowing for an extensive list of compounds including those analyzed by TO-14A. Utilizing SIM or SIS modes, TO-15 can detect compounds in the pptv range while TO-14A is limited to ppmV and high ppbV ranges. TO-15 sets performance criteria supporting alternative but equivalent sampling equipment not allowed by TO-14A. TO-15 also includes enhanced analytical protocols yielding a higher percentage of qualified data. Overall, the TO-15 GC/MS approach provides more scientifically defensible data, a wider compound list, and lower detection limits. More

Q: Can Torrent report TO14A?

A: Yes. Although our default method is TO-15, Torrent can analyze samples through both the GC/MS as well as the GC (we use a split sample technique). Choosing the TO14A method is more a function of how the field samples are taken.

Q: Does Torrent analyze for petroleum hydrocarbons?

A: Torrent analyzes for Gasoline range Hydrocarbons by TO-3, and TPH Diesel range compounds by NIOSH 1550/EPA 8015B, both GC methodologies. TPH Gas range analysis is performed with either a sample taken in a Tedlar Bag or Suma canister while TPH Diesel range is analyzed after extraction of sorbent material from specialized sample media. For more detail, please feel free to contact our Project Management department.

Q: Should I use Tedlar bags or Suma Canisters for collecting samples?

A: Suma canisters are generally preferred for collecting samples for several reasons: The holding time is much longer with a canister– 30 days vs. 72 hours for a Tedlar bag (some parameters as short as 24 hours); unlike a bag, canisters reduce or eliminate leaking due to an inadvertent puncture or a leaking seal; and the inert nature of the canister allows for trace level analysis of compounds without significant contribution from background contaminants sometimes found in Tedlar bags.

Tedlar bags are appropriate when sampling at sites with significant contamination from petroleum fuel sources, sites being sampled for only sulfur or atmospheric gases, or from chlorinated solvent contaminated sites where expected HVOC levels are in the ppmV or high ppbV range. Tedlar bags are ideal for immediate, onsite analysis but less appropriate when samples are being transferred to a stationary lab site.

Tedlar bags are never appropriate when sampling to Indoor air ESLs or when Naphthalene is a compound of concern.

Q: What sampling equipment is supplied by Torrent?

A: For sampling of volatile compounds Torrent supplies 6L Suma canisters, sampling manifolds with particulate filter (equipped with dual ports for use when employing purge canisters), flow controllers preset for desired sampling time (1, 3, 8, 12 or 24 hours), and intial/final vacuum gauges to feel confident that enough sample was collected for accurate analysis. For collecting ambient air samples, a U-shaped regulator is provided along with a canister and attached vacuum gauge.

1 liter Tedlar bags are available upon request but are subject to a fee.

For air sampling requiring sorbent tubes or filters, pump devices or special tubing, Torrent can arrange for the materials to be shipped to you directly or can supply you with the contact information so you can make specific arrangements with our preferred supplier. Just contact Project Management and they will be able to assist you in securing whatever you require.

Q: How much does Torrent charge for canister and sampling accessory rental?

A: Torrent does not charge a separate rental fee for any equipment that we supply. As long as the parameters of your sampling event are communicated to our PM department with at least 48hrs notice, all batch certified canisters (and accessories) can be delivered to your place of business or sampling site.

Q: How do I sample with the Suma canister?

A: There are two sampling techniques normally employed: Grab sampling which is a simple matter of opening the canister for a set period of time, and soil vapor sampling which involves using a manifold/flow controller system. Please click on the link below for detailed instructions for both techniques. More

Q: What reporting limits can I expect for air analysis?

A: Reporting limits are dependent on several factors. Torrent’s initial Reporting Limits are below the current ESLs for most compounds of interest. That being said, the final reporting limit is a function of the amount of sample available for analysis (are the inches of Mercury at –5 to 0 or will the lab have to dilute the sample to the correct psi?) , the sample requires dilution due to high concentrations of compounds of interest and/or interfering compounds and, in some cases, matrix interference such as high concentrations of sultanate compounds or fixed gases (methane, ethane, ethane, CO2, etc), resulting in the need to dilute the sample prior to analysis. The last two situations are rarer than the first, but happen occasionally.

Q: Do I have to take separate samples if I need both TO-15/TO-14A/TO-3 and the Fixed Gases?

A: No. As long as the canisters are full, all analyses can be performed from the same sample. If the sample volume is low, it will affect final reporting limits. However, if multiple techniques are requested, Torrent will perform the most sensitive technique first. Because fixed gases are reported in % and/or ppmV ranges, slight dilution factors due to low pressure does not affect the final reporting limits as dramatically as the TO methods.

Q: What are the cost differences between requesting “batch clean certification” and “individual clean certification”?

A: There is no associated cost with batch certification. Individual can certification is available at a minimum charge of $100 per canister. This charge will cover almost all scenarios with the exception of a very specialized compound list, or pptv detection limit requests. If you have very specialized criteria, please contact Project Management so that they may be able to assist you with correct pricing.

Q: What is the difference between the canisters “batch certification” vs. “individual certification”?

A: Batch certification is defined by the quantity of canisters than can be “cleaned” at any one time. Torrent’s cleaning station can accommodate 10 canisters at a time. To certify the batch, one canister from each cleaning process is certified clean to below <0.2 ppbv Any associated accessories may be interchanged amongst the batch cleaned canisters.

Individual certification requires that each canister supplied to a client be certified to below the method detection limit for every compound that will be analyzed (58 on our longest list). Any associated accessories are NOT interchangeable with other individually or batch certified canisters.

Q: Why would I need individually certified canisters?

A: For most applications, individually certified canisters would not be necessary. However, when sampling to residential indoor air specifications or to risk assessment criteria requiring pptv (parts per trillion by volume) sensitivity, individually certified canisters may be critical to a successful sampling event. If you can supply your target list of compounds and required reporting limits to our project management team, they will be happy to assist you in determining what best suits your needs.

Q: When should I request an Air Blank?

A: When sampling for Soil Vapor in the field, it may be wise to request an ambient air blank that you can use to determine what is present in the background air at your sampling site, versus what is present in the samples you are collecting. Often time the information received from the analysis of the ambient air blank will be instrumental in determining what how to use the data found in the actual samples.

Q: When do I need to use Purge Canisters?

A: When sampling soil vapor it may be necessary to purge the first 200 –500 ml of sample from the well/boring in order to ensure a representative sample is collected. Torrent’s sampling manifolds are specifically designed for this purpose and purge canisters, as all canisters, can be provided at no extra charge. Just be sure to let our Project Management team know how many purge canisters you require with your order.

Q: How do I know I have collected enough samples using a 6 L Suma Canister?

A: When passively collecting samples (ambient air), simply open the valve and the canister will collect the sample at the pre-set flow rate determined by the orifice size (1, 3, 8, 12 or 24 hrs). The collection time may vary by 20 to 30 minutes on either side of the time chosen due to room temperature and/or ambient pressure.

When using a sample pump to force flow, the canister will still only accept the maximum flow allowed by the orifice. This helps ensure that the flow rate into the canister is constant and representative of the entire sampling event. When the Hg reading on the gauge is at or slightly below 5 inches, the canister is full.

Q: What does it mean if the Hg inches are less than -5 after the sampling time has elapsed?

A: All samples prior to analysis must be pressurized to between -5 and 0 psig. So if the inches of Hg are less than -5, reporting limits will be elevated.

Unless extreme temperature or pressure changes have occurred in the ambient environment, passively collected samples will normally not suffer from this situation. However, if actively collected samples display greater than 5 inches of Mercury, it is likely that the pump flow rate was set too low.

Q: What units does Torrent use when reporting results?

A: Because the instruments are calibrated in ppbv, Torrent uses ppbv as the default reporting unit for all VOC analysis. Per client request, data can be converted and reported in µg or mg/m³ understanding that the pressure and temperature are set as constants (atmospheric pressure of 24.46 and ambient temperature of 25°C). If you have data you would like to convert from one unit to the other, please refer to our conversion table.

Inorganic and semi-volatile analytical data is reported in µg/m³ or mg/m³ as the method employed requires.